Method of Determining Quality of Service for On-Line Gaming in a Network

ABSTRACT

In a method and a device for determining the perceived quality of service for a wireless gaming service a perceived gaming quality is determined based on measurable game and transport parameters.

TECHNICAL FIELD

The present invention relates to a method and a device for determiningthe on-line gaming quality of service in a network.

BACKGROUND

Today on-line gaming, with popular games like Counter-Strike and Worldof Warcraft, has become one of the most important services in wirelineInternet access. With the introduction of new high performance wirelessnetworks on-line games can now also be played over a radio network.

In radio and fixed networks the Quality of service or Quality ofexperience (QoS or QoE), and how the end-user perceives a service, hasbeen measured for speech for many years, and new methods emerge tomeasure the quality of multimedia services. Typically, measurements aredone with objective models, which take measurable input parameters andcalculates an opinion score representing the end-user perceived quality.

Studies have been done to investigate how network properties, such aspacket latency, affect the quality of on-line gaming, see for example T.Lang, \User Experience while playing Halo with network delay or loss,”Centre for Advanced Internet Architectures, CAIA, Swinburne Universityof Technology, Tech. Rep. 031205A, December 2003. [Online]. Available:http://www.caia.swinburne.edu.au/ and P. Branch and G. Armitage,\Measuring the auto-correlation of server to client traffic in FirstPerson Shooter games,” Swinburne University, December 2003. [Online]Available: http://www.caia.swinburne.edu.au/, which both address theplaying phase of on-line gaming.

However, there exist no way for a service provider to measure theperceived quality of an on-line gaming session using a wireless orwireline connection.

Hence, there exist a need for a method and a system that enables aservice provider to measure the perceived quality delivered to asubscriber of an on-line gaming service.

SUMMARY

It is an object of the present invention to overcome or at least reducesome of the problems as set out above.

It is another object of the present invention to provide a method and adevice that is capable of providing an objective quality measurement foran on-line gaming session.

It is yet another object of the present invention to provide a modelthat can be used to provide an objective quality measurement for on-linegaming.

These objects and others are obtained by the method and system as setout in the appended claims. Thus, in accordance with the presentinvention the end-user perceived quality of on-line gaming is estimatedbased on measurable game and transport parameters. Hereby it is possibleto provide an accurate measure for an ongoing on-line gaming session forthe service provider.

The estimated quality may take into account different phases of on-linegaming, i.e. periods during an on-line gaming session having differentdata transfer characteristics or real time constraints. Examples of suchphases can be a load phase where the game or game data is loaded andplaying phase where the game is played on-line. The present inventionenables the service provider to obtain an objective quality measure thattake different on-line gaming phases into account thereby providing ameasure better reflecting the perceived service quality.

In accordance with one embodiment, the estimated quality is based ongaming parameters, such as loading time, and on network transportparameters, such as packet loss, packet latency/delay, and packetjitter. In addition the input parameters can be either measureddirectly, or estimated based on other measurement parameters. Forexample the game loading time can be estimated based on transportparameters like throughput.

The output of the on-line gaming model is an end-user perceived gamingquality score, typically a numerical value representing a Mean OpinionScore (MOS) that can be used to determine the quality of servicedelivered to a particular subscriber.

The model can advantageously be tuned using results from subjectivetest, where test persons have been playing a game and giving a qualityscore, which then are used to calculate a MOS score.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail by way ofnon-limiting examples and with reference to the accompanying drawings,in which:

FIG. 1 is a view illustrating a device for determining the quality ofservice for an on-line gaming service, and

FIG. 2 is a flow chart illustrating different steps performed whendetermining the quality of service for an on-line gaming service.

DETAILED DESCRIPTION

In FIG. 1, a device 100 for determining the Quality of Service for anon-line gaming session over a network is shown. The device comprises amodeling unit 101. The modeling unit 101 is connected to a number ofinput ports 103, 105, 107 and 109. The input ports provide the modelingunit 101 with input data useful as input data in a prediction model. Forexample the input port 103 may provide values related to packet latency,the input port 105 may provide values related to map load, i.e. gameloading time, the input port 107 may provide values related to packetloss and the input port 109 may provide values related to packet jitter.Using the different input data provided through the input ports 103-109,the modeling unit calculates a MOS score representing the end-userperceived quality. The model used can be any suitable model such asdescribed below and can be implemented using a computer program 113loaded into the modeling unit 101. The MOS score is then used as a basisfor determining the quality provided to the end-user in an output unit111.

The input parameters are not limited to the ones described above. Otherinput parameters from the transport layer and from the gamingapplication can also be used to get a good prediction of the on-linegaming quality.

In one embodiment of our invention the output MOS can be calculatedusing a linear model. In accordance with another embodiment a non-linearmodel is employed.

For example the modeling unit 101 may be adapted to generate an indexwhich may be termed a Game Quality Index, GQI, as follows. The GQIquality models estimates a predicted Mean Opinion Score, MOS, from theinput function, which depend on variables such as latency x_(latency)and map load y_(mapload). A parameter GQI_(BASE) can be set to steer themodel initial value, i.e. maximal model output if no degradation fromlatency x_(latency) and map load y_(mapload) occurs. Another parameterGQI_(MIN) adapts output to MOS, where minimal MOS value is 1. Thefunctions can be set to only exist in the span [0; 1]. If no other inputrelated to other variables such jitter and packet loss is used a linearGQI_(MOS) model can be formulated as:

GQI _(MOS) =GQI _(MIN) +GQI _(BASE)*(Q _(xlatency))*(Q _(ymapload)))  Eq1

where

Q _(xlatency) =a*x _(latency)+1,2 (or some other suitable constant)  Eq2

Q _(ymapload) =b*y _(mapload)+1,4 (or some other suitable constant)  Eq3

Where a can be 0.0053 in one embodiment and b can be 0.0075. A linearmodel as GQI_(MOS) demands boundary conditions to prevent MOSpredictions outside the scale. For Q_(xlatency) predetermined maximumand minimum values are determined. For example values below 40 and above225 ms can be set to model maximum respective minimum values.Q_(ymapload) can also have predetermined boundary conditions. Forexample boundary conditions of below 55 and over 180 seconds can be usedto ensure an authorized MOS value.

The gaming quality can also be calculated using a non-linear function.For example the following equations may be used:

GQI _(MOS) =GQI _(MIN) +GQI _(BASE)*(Q _(xlatency))*(Q _(ymapload))  Eq4

Where

Q _(xlatency)=1/(1+(alpha*x _(latency))̂3))  Eq5

Q _(ymapload)=0.6−beta*atan((1/gamma)*(y _(mapload) −TH))  Eq6

where constants alpha, beta and gamma are 110, 2.3 and 165 respectively.The two Q degradation functions exists only within the span [0,1], andno bounding conditions are needed. This model has a more smooth behaviorthan the linear model and is more suited to the data set. Due tomeasured patience from the users when entering the game, the thresholdparameter TH equals 220 and steers the quality degradation in theQ_(ymapload) function together with beta and gamma.

The gaming model can also take the effect of packet loss and jitter intoaccount when estimating the perceived quality. In accordance with oneembodiment the Gaming Quality Index can then be modeled and calculatedas:

GQI _(MOS) =GQI _(MIN) +GQI _(BASE)*(Q _(xlatency))*(Q _(ymapload)))*(Q_(zjitter)))*(Q _(wpacketloss))  Eq7

where

Q _(zjitter)=−0.0022*z _(jitter)+1  Eq8

Q _(wpacketloss)=−0.24*w _(packetloss)+1  Eq9

The jitter is in Eq8 above is given in milliseconds and the packet lossin percent. The maximum boundary for jitter can be set to 450 ms and forpacket loss the maximum boundary can be set to 4%. The parameters andconstants in equations 8 and 9 can of course be adjusted to suit aparticular application.

A gaming quality determination can be implemented at various locationsin a network. It can be implemented in a drive test tool for a radionetwork, in any computer running an on-line game, and in measurementlocations in a network, but then producing a score representing themeasurement location, not the end-user terminal or computer. Theimplementation can also be done in a network but the input parametersare reported from a computer running an on-line game.

In FIG. 2 a flowchart illustrating different steps performed whendetermining an objective online game quality of service is shown. First,in a step 201, data for a number of different parameters related to theperceived service quality are collected. The parameters may include anyof the parameters above or any other relevant parameters. Next in a step203, the collected data is used as input in a model modeling theperceived service quality based on both measurable game parameters andmeasurable transport parameters. The model used in step 203 canadvantageously be tuned to correspond to experiences in a test group ofpeople. In step 203 the input data as fed to the model yields aprediction as to what a real person would think of the service qualitybased on the specific set of input data.

Finally, in a step 205, the prediction generated in step 203 is used asa determination of the current level of service quality at a particularpoint in a wireless or fixed network, typically at an end-user device orat any other location in the network where the service provider isinterested in knowing the quality of service.

Using the method and device as described herein input parameters areused to calculate a quality score for on-line gaming which can be usedby a service provider to monitor and ensure that services are deliveredto subscribers in accordance with what the subscribers expect. Theinvention further provides for an analysis of different gaming phases,such as gaming load phase and gaming playing phase.

1-11. (canceled)
 12. A method of determining the perceived quality ofservice for an on-line gaming service comprising determining a perceivedgaming quality based on measurable game and transport parameters. 13.The method of claim 12, wherein the game parameters include loadingtime.
 14. The method of claim 13, wherein the transport parametersinclude at least one of packet loss, packet latency/delay, packetjitter, and throughput.
 15. The method of claim 12, wherein thetransport parameters include at least one of packet loss, packetlatency/delay, packet jitter, and throughput.
 16. The method of claim12, wherein determining perceived gaming quality comprising determiningperceived gaming quality by taking into account different phases ofon-line gaming.
 17. The method of claim 16, wherein the different phasesinclude a load phase and a playing phase.
 18. A device configured todetermine the perceived quality of service for an on-line gamingservice, the device comprising: one or more circuits configured todetermine a perceived gaming quality based on measurable game andtransport parameters.
 19. The device of claim 18, wherein said one ormore circuits are configured to determine a perceived gaming qualitybased on loading time as one game parameter.
 20. The device of claim 19,wherein said one or more circuits are configured to determine aperceived gaming quality based on at least one of packet loss, packetlatency/delay, packet jitter, and throughput as one transport parameter.21. The device of claim 18, wherein said one or more circuits areconfigured to determine a perceived gaming quality based on at least oneof packet loss, packet latency/delay, packet jitter, and throughput asone transport parameter.
 22. The device of claim 18, wherein said one ormore circuits are configured to determine a perceived gaming quality bytaking into account different phases of on-line gaming.
 23. The deviceof claim 22, wherein the different phases include a load phase and aplaying phase.
 24. A computer program product for determining theperceived quality of service for an on-line gaming service, the computerprogram product comprising computer program code embodied in acomputer-readable storage medium, the computer program code comprising:code configured to determine a perceived gaming quality based onmeasurable game and transport parameters.
 25. The computer programproduct of claim 24, wherein said code is configured to determine aperceived gaming quality based on loading time as one game parameter.26. The computer program product of claim 25, wherein said code isconfigured to determine a perceived gaming quality based on at least oneof packet loss, packet latency/delay, packet jitter, and throughput asone transport parameter.
 27. The computer program product of claim 24,wherein said code is configured to determine a perceived gaming qualitybased on at least one of packet loss, packet latency/delay, packetjitter, and throughput as one transport parameter.
 28. The computerprogram product of claim 24, wherein said code is configured todetermine a perceived gaming quality by taking into account differentphases of on-line gaming.
 29. The computer program product of claim 28,wherein the different phases include a load phase and a playing phase.